feat: Implement session Git state management and commit operations (#318734)

* feat: Implement session Git state management and commit operations

* refactor: Remove unused methods and imports from AgentService

src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts

@@ -128,6 +128,7 @@ class MockAgentService implements IAgentService {
 	unsubscribe(_resource: URI, _clientId: string): void { }
 	async shutdown(): Promise<void> { }
 	async authenticate(_params: AuthenticateParams): Promise<AuthenticateResult> { return { authenticated: true }; }
+	getAuthToken(): string | undefined { return undefined; }
 	async resourceWrite(_params: ResourceWriteParams): Promise<ResourceWriteResult> { return {}; }
 	async resourceList(uri: URI): Promise<ResourceListResult> {
 		this.browsedUris.push(uri);
@@ -167,6 +168,7 @@ class MockAgentService implements IAgentService {
 	}
 	async createTerminal(): Promise<void> { }
 	async disposeTerminal(): Promise<void> { }
+	async invokeChangesetOperation(): Promise<{}> { return {}; }
 
 	dispose(): void {
 		this._onDidAction.dispose();